Background: RNase P-mediated cleavage of target RNAs has been proposed as a promising
tool for gene silencing. Ets-2 proto-oncogene controls the expression of a wide variety of
genes involved in cancer and immunity.
Objective: Construction of a functional RNase P-based ribozyme (M1GS303) that targets Ets-2
Methods: The accessible sites for targeting of Ets-2 mRNA were identified by footprinting analysis.
M1GS303 ribozyme was constructed by cloning. The activity of the ribozyme in the presence
or absence of spiramysin in E. coli cells and human cell lines was quantified by RT-PCR. The efficiency
of the ribozyme in silencing the endogenous expression of Ets-2 in human cell lines was
examined by RT-PCR, western blot and immunofluorescence analysis.
Results: In E. coli cells co-transformed with plasmids bearing M1GS303 and the ets-2 target gene,
Ets-2 mRNA was decreased by 93% 12h after IPTG induction in the absence, and after 4h in the
presence of spiramycin. Ets-2 was rapidly downregulated in the human embryonic kidney cell line
HEK293 and the T-cell line Jurkat transfected with an M1GS303 plasmid; the silencing effect of
M1GS303 was considerably faster when the cells were cultured with spiramycin. In Jurkat cells,
Ets-2-downregulation resulted in upregulation of the expression of IL-2, IL-4 and IFN-α cytokine
genes that have Ets-2 binding sites on their promoters, whereas it had no effect on the expression
of the IL-10 gene that lacks Ets-2 binding sites on its promoter.
Conclusions: M1GS303 ribozyme cleaves effectively Ets-2 mRNA in bacteria and mammalian
cells, and its activity is enhanced by spiramycin. Downregulation of ets-2 gene in the T-cell line
Jurkat upregulates IL-2, IL-4 and IFN-α cytokine genes. M1GS technology may be a better alternative
to conventional gene-interference therapies and the delineation of the effects of gene silencing
in various pathologies.